The present invention is directed generally to the problem of oxides rolled onto the surfaces of metal strips in a rolling mill, and particularly to identifying and quantifying rolled-on oxides from video images of surfaces containing oxides.
Oxide residues sometimes occur on the bare metal surfaces of hot rolled and cold rolled aluminum alloys. The formation of such residues is not completely understood and, as a consequence, the elimination of such oxides has not been totally effected. For aesthetic reasons it is preferred that the surfaces of bare metal not contain any substantial amount of oxides.
Since the elimination of oxides has not been effected in rolling processes, the severities of the oxides must be evaluated so that steps can be taken to at least attempt an alleviation of the problem.
Current evaluation practices require visual inspection by trained quality assurance personnel. Such personnel visually examine small pieces of metal samples that have been removed from a wrap or wraps of large coils of the metal, and assign grades to the oxide residues. The grades represent respective oxide severities.
The human eye has limited resolution and sensitivity so that the scoring or grading process provides finite, discrete grade levels, as opposed to a continuous or infinite number (at least theoretically) of grade levels.
In addition, the task of visually inspecting metal samples is laborious, and the consistency and accuracy of the grading process is not always reliable.